\documentclass{article}
\makeatletter
\def\ps@mycustomheadings{\let\@mkboth\@gobbletwo
\let\@oddfoot\@empty\def\@oddhead{\reset@font\hfill\thepage
}\let\@evenfoot\@empty\let\@evenhead\@oddhead}
\makeatother
\pagestyle{mycustomheadings}
\begin{document}
This is a test.
\end{document}